Feeling like a fossil but don't want to wait 100 million years? Now you can make them just like Mother (Earth) used to make! Don't be petrified, it's not as hard as you think. These mold and cast fossils are great for school, home, or as a prank on an archaeological dig. Whether you want to make a fossil of insects, animals, your thumb, corded telephones, or 8-track tape players, you can do it all with this method in about 20 minutes.
These are made in the same way many fossils are made: The scene opens to a muddy bog. Bug crawls on to muddy bog, dies. Bug body leaves an imprint. Over time, sediment crystallizes into concretions, and fills in the imprint the bug made. Millions of years later, you have rock bug! You can learn all about the ways in which fossils are created here, and more about fossils on wikipedia. For now, let's make our own!
- What: Homemade Fossils!
- When: Now, and lasting for 100 million years
- Concepts: fossils, earth science, sedimentation, paleontology, chemical reactions, casting
- Time: ~ 20 minutes
- Cost: ~ $0.25 per fossil
- Rockite (or other fast cement)
- Paper cups
- Sculpting Clay
- Things to fossilize (plastic bugs work well)
- Mixing stick
- Mixing cup
- Food coloring (optional)
Time to take this earth science class back old school!
Step 1: Prepare Clay
This is going to act as the peat bog that our bug is going to fall trip in to. Start by cutting your paper cup down to a modest height or start with one of those small paper medicine cups. Smush in some clay at the bottom, and smooth out the top surface with your finger, so that it snugs against the paper cup wall.
What's great is your clay is reusable fossil after fossil, so you don't have to worry about using too much.
Step 2: Imprint!
Choose your favorite plastic bug, plastic animal, appliance, or finger to imprint on the surface of your clay. If your creature has lots of legs or antennae, make sure to squish each one individually into the clay surface. If you mess up, simply smooth out the clay and try again. Once you're done, remove the creature itself and get ready to cast.
Neatly, through decomposition and mineralization, nature has a pretty nifty way of disappearing rock-bedded creatures too through petrification.
Step 3: Casting Time!
Here comes the sediment! Rockite is great for making fast fossils, as is Quikrete. Grab a mixing stick and a separate mixing cup for this process. While they do have mixing ratios on the box, I prefer to just throw in a couple spoonfuls, then add water and continuously mix until you get a thick porridge consistency. If it gets too watery, simply add in a little more cement mix.
Neatly, as soon as the cement hits the water, the chemical reaction begins. You can see it by bubbling and feel the cup growing warmer. Optionally, you can add food coloring to the mix to give it a tint. When you're ready, pour the cement in to your clay cup so that the whole fossil is covered, and a little more to give it a cement base to live in.
Concretions like this are actually how the sedimentary rocks we found fossils in are formed. Usually it takes a lot of time and a lot of pressure when Earth does it. But hey, these fossils have places to be, people!
Gentle Warning: Cement mixes can be irritating to skin, eyes, and mouth as stated on the package. Take necessary precautions, and wash your hands after use. If something doesn't feel right, pause the activity, and take care of what's wrong first. The fossils can wait. That's what they're good at.
Step 4: Wait, Peel, and Remove!
Set your rocks to solidify in a place they won't be disturbed. After about 15 minutes, you can feel to see if the tops are solid, and if the cement is beginning to cool. When you just can't wait any longer, it's time to dig your fossils out of their sedimentary layer, and reveal them!
Step 5: Fresh Fossils!
Hot out of the Earth, you have fresh fossils! Give them a rinse. Take them on walks. Name them. Read to them. Make some more. Read about Earth Science and Paleontology to understand them better. Give them to friends. You have pulled off in 20 minutes what takes the Earth sometimes several quadrillion times longer. Congratulations!
I would be super excitedto see your Homemade Fossils, too! I can give out 3 month Pro Memberships to the first three people that post photos below! Regardless, I would love to hear your thoughts and comments!
As always, have fun and keep exploring!